The invention relates to supporting a substrate in a chamber.
In substrate processing chambers, particularly vacuum processing chambers used to deposit and/or etch substrates, such as semiconductor wafers, a plasma may be used to process a surface of the substrate. The plasma may be formed by an electric field that is created between electrodes in the chamber, or is induced in the gas by passing an electrical current through a coil outside the chamber. However, the plasma in the processing chambers may react not only with the surface of the substrate being processed but with other exposed surfaces as well. The rate of reaction and/or erosion is dependent on the surface properties, such as a resistance of the exposed material to the active species of the plasma. The plasma may extend across the surface of the substrate all the way to its edge.
A typical configuration for supporting a substrate 15 exposed to a plasma on a pedestal assembly in a processing chamber 330 is shown FIG. 1a. The pedestal assembly 340 includes a series of lower supports 344, 346 and a series of outer rings 348, 350 surrounding a substrate support member 343. The upper outer ring 350, which may be a focus ring composed of a dielectric material, may also be exposed to the deleterious effects of the plasma as it extends over the edge of the substrate 15. The outer ring 350 may be made of alumina to be resistant to the plasma.
A close-up of the construction of an upper corner (see circle 349) of a prior art pedestal assembly 340 is shown in FIG. 1b with a dielectric collar ring 352, which may be a focus ring 350. The focus ring may preferentially direct gas species onto the substrate 15. The collar ring 352 surrounds the substrate 15 to be processed. The substrate support member 343, which may be made of aluminum, may be configured to extend to the edge of the substrate 15 it supports to provide more uniformity in the temperature of the substrate 15. The collar ring 352, which may be made of alumina or other plasma compatible ceramic material, surrounds the edge of the substrate 15 and acts as a barrier to protect the sidewalls of the aluminum substrate support member 343 from exposure to plasma. The larger thermal expansion coefficient and related expansion of the aluminum support member 343 may be accommodated by having enlarged dimensions for the surrounding collar ring 352 which has a comparatively small coefficient of thermal expansion. Therefore, large expansion gaps 360, 362 may be provided between the outer perimeter of the substrate support member 343 and the collar ring 352 so that as the aluminum support member 343 expands it does not cause the surrounding collar ring 352 to fracture. Process gas may leak through the gaps, or a plasma may be formed therein that leads to corrosion or erosion of material adjacent the gaps.
Similar substrate support pedestal assemblies can be used in the other processing chambers, for example a side exhaust-metal etch chamber (FIG. 2a), a bottom exhaust metal deposition/etch chamber (FIG. 2b), or a chemical vapor deposition chamber (FIG. 2c).
Therefore, it is desirable to have a support assembly capable of compensating for the thermal expansion of one or more components of the support assembly. It is further desirable to have an erosion resistant support assembly. It is also desirable for a support assembly to provide a gas flow restrictive seal. It is still further desirable to reduce the gaps within a support assembly.
The present invention satisfies these needs. In one aspect of the invention, a substrate support assembly comprises a support comprising a substrate supporting surface and a collar comprising at least one slit.
In another aspect of the invention, a substrate support assembly comprises a support comprising a substrate supporting surface, the support having an outer diameter, and a collar around the support, the collar having an inner diameter less than the outer diameter of the support.
In another aspect of the invention, a substrate processing chamber comprises a substrate support assembly comprising a support and a collar at least partially around the support, the collar comprising a slit, a gas distributor, a gas energizer, and a gas exhaust, whereby a substrate received on the support assembly may be processed by gas introduced through the gas distributor, energized by the gas energizer and exhausted by the gas exhaust.
In another aspect of the invention, a method of supporting a substrate in a process chamber and processing the substrate in the process chamber comprises supporting the substrate on a support assembly in the process chamber, the support assembly comprising a collar at least partially around a support, providing an energized process gas in the process chamber, heating at least a portion of the support assembly, and providing a slit in the collar that is sized and shaped to compensate for a thermal expansion of the support or the collar.
In another aspect of the invention, a method of fabricating a substrate support assembly comprises forming a collar sized to fit around a support and forming a slit in the collar.
In another aspect of the invention, a method of fabricating a substrate support assembly comprising forming a support having an outer diameter, forming a collar having an inner diameter smaller than the outer diameter of the support, and providing the collar around at least a portion of the support.
In another aspect of the invention, a collar for a substrate support assembly comprises a ring adapted to fit around a support and a slit in the ring.
In another aspect of the invention, a collar for a support assembly comprises a ring adapted to fit around a support and an inner surface on the ring adapted to be biased against an outer surface on the support.
In another aspect of the invention, a substrate support assembly comprises a support comprising a substrate supporting surface and a collar abutting the support.
In another aspect of the invention, an apparatus comprises a first split ring configured to substantially surround a substrate support surface of a substrate support member, said split ring having an inner surface in substantially continuous contact with a perimeter surface of said substrate support member, wherein when said split ring is positioned adjacent to said substrate support member a top surface of said split ring is approximately an outward extension of the substrate support surface of said substrate support member.
In another aspect of the invention, a method of reducing the loss of material at the edge of a substrate support member in a processing chamber comprises providing a recess at the perimeter of the substrate support member and providing a first split ring in said recess with an inside surface of said ring in substantially continuous contact with an inside surface of said recess, such that a top surface of said split ring forms an extension of a substrate support surface of said substrate support member.